川西气田白云岩储层二维核磁共振测井气水识别方法

川西气田雷口坡组四段白云岩储层具有良好的天然气勘探开发前景，但是储层分布具有较强的非均质性，利用常规测井和一维核磁共振测井方法判断储层流体性质存在多解性．通过分析川西雷四段白云岩储层地质特征与测井响应特征，开展岩心二维核磁共振实验，明确了实验室分析与测井过程中环境、参数等影响因素，建立了岩心分析结果的校正方法，明确了钻井液、束缚流体、可动水与天然气信号在二维核磁共振测井中谱分布区间，建立了基于T₂-T₁、T₁/T₂（R）的白云岩储层二维核磁共振测井气水识别图版．利用图版对川西雷四段储层流体性质开展评价，二维核磁共振测井解释结论得到了实钻测试结果的验证，该气水识别方法填补了常规测井、一维核磁共振测井在评价储层气水关系中的缺陷，可有效解决白云岩储层流体性质判别难题．

A Two-Dimensional NMR Logging Method for Gas-Water Identification in Dolomite Reservoir of the Western Sichuan Gas Field

The dolomite reservoirs in the fourth member of Leikoupo formation of the western Sichuan gas field have good prospects for natural gas exploration and development. However, the conventional and one-dimensional nuclear magnetic resonance (1D NMR) logging data are not sufficient for a definitive classification of the reservoir fluid type, likely because of heterogeneity of the reservoirs. Through geological characteristics analysis, log response analysis and two-dimensional (2D) NMR experiment, the environmental factors and technical parameters leading to the differences between the laboratory results and actual logging data were determined. According to the analysis of T₂-T₁ and T₁/T₂ (R) differences, the distribution range of drilling fluid, bound fluid, movable water and natural gas signals in the 2D NMR spectra was delineated to build a gas-water 2D NMR identification chart. The results obtained using the identification chart were verified with the actual drilling test results. Complementary to conventional and 1D NMR logging, the 2D NMR identification method was proposed, and can be used to determine the fluid properties in the dolomite reservoirs effectively.